1/4 ruby or pink grapefruit, cut into small chunks, remove seeds2 tablespoons agave syrup or honey12 fresh mint leaves, roughly torn1/2 cup pink grapefruit soda or flavored mineral waterMint sprigs for garnishPut the grapefruit pieces, agave and mint in a cocktail shaker. Using a muddler, smash the fruit until the juice is released. Add one cup small ice cubes to the shaker with the half cup soda; attach the lid and shake furiously until combined. Divide between two rocks glasses, add more ice if desired, and top off with additional soda. Stir, garnish with mint sprigs and serve.